This Invention relates, broadly, to hydroponics. More particularly, the invention relates to an apparatus or installation, and to a method, for the hydroponic cultivation of plants, the apparatus or installation, and the method, being suitable for, but not limited to, the hydroponic cultivation of strawberries.
According to one aspect of the invention there is provided an apparatus or installation for the hydroponic cultivation of plants, the apparatus or installation including:
a plurality of horizontally spaced plant support structures each extending upwardly from a lower extremity thereof to an upper extremity thereof, each of which support structures includes a plurality of rooting compartments containing plant rooting medium, the compartments of each structure being arranged in a series extending over the height of the structure and each rooting compartment having a wall provided with at least one opening for permitting foliage of a plant rooted in the rooting medium in the compartment to protrude from the compartment;
a water feed network in flow connection with and fed by a water supply, and including a plurality of water flow conduits leading from the supply to the rooting compartments for conducting water from the supply to each of the rooting compartments;
a water drainage network including a plurality of water drainage conduits in flow connection with and leading away from the rooting compartments, for conducting water away from the rooting compartments; and
water circulation means for circulating water from the supply in succession through the feed network, then through the rooting compartments of the support structures and then through the drainage network.
In principle the water circulation means can circulate water from a supply such as a mains water supply, optionally through a nutrient dosing tank where nutrients are added to the water and dissolved therein, once through the apparatus or installation, after which the spent water can be discarded to waste. If, on the other hand, as is often the case, it is desired to re-use the spent water and any dissolved nutrients remaining therein, the water supply may, instead, be a reservoir for holding the water which is fed by the feed network, the feed network being in flow connection with, and being fed with water discharged from, the reservoir, and the water drainage network leading from the rooting compartments to the reservoir for conducting water from the rooting compartments to the reservoir, the reservoir, the water feed network, the rooting compartments of the plant support structures and the water drainage network together forming a water circulation circuit, and the water circulation means forming part of the circuit, for circulating water around the circuit.
The aforegoing sets forth what are regarded as the important features of the broad idea of the apparatus or installation aspect of the invention, the features set forth hereunder being optional features which can be included or omitted from this aspect of the invention, as desired. In particular it is to be noted that when a number of features are grouped together hereunder in a particular optional or preferred embodiment of the invention, this is a matter of choice and it is to be explicitly understood that any one of such features may be altered, omitted or substituted by an equivalent, without expanding on the scope of the invention or extending the disclosure thereof. More particularly, it is explicitly noted that any feature set forth hereunder can be imported into the broad idea of the invention set forth above, without the necessity of importing any other feature of the invention set forth below into that broad idea, whether or not such feature forms part of the same preferred or particular embodiment.
When the various parts of this aspect of the invention are relatively small and portable, being releasably connected or readily disconnectable from one another, it can be regarded as an apparatus; and when they are relatively large and more or less permanently connected to one another, this aspect of the invention can be regarded as an installation.
While each plant support structure may in principle be any structure extending between lower and upper extremities thereof, such as a wall, slab or the like, which provides the series of compartments containing the rooting medium, it is preferably in the form of a plant support column, which may be elongated, the series of compartments extending over the length, ie over the height, of the column. Each plant support column may extend substantially vertically and each plant support column may include a sleeve of flexible material containing the rooting medium, the sleeve being divided by a plurality of constrictions, spaced along the length of the column, into the rooting compartments. Each sleeve may be of water-impermeable plastics sheet material, each constriction being formed by a tie extending circumferentially around the sleeve, for example a plastics plant tie or plastics electrical cable tie, under tension and forming an associated constriction in the sleeve. In other words, each sleeve may be of water-impervious plastics material, each constriction in said sleeve being provided by a tie under tension extending around the associated sleeve, each opening in each compartment wall being provided by a slit in the flexible material.
The water feed network may comprise a water feed reticulation system leading from the reservoir to each plant support structure, there conveniently being a water feed manifold, forming part of the feed reticulation system, extending alongside the series of rooting compartments of each plant support structure, a plurality of irrigation connections, such as self-compensating irrigation nozzles which compensate for variations in supply pressure arising e.g. from differences in static head or height, or irrigation tubes such as capillary tubes or dripper tubes, which irrigation connections may thus be of the drip irrigation type, leading from each water feed manifold respectively into the rooting compartments of the plant support structure associated with that water feed manifold, preferably at a high level into each rooting compartment. The water feed reticulation system may be at a high level, at or above the upper extremities of the plant support structures, each water feed manifold being suspended by, and depending downwardly from, the part of the feed reticulation system upstream thereof. In a particular construction, accordingly, the water flow conduits of the water feed network may include a plurality of water feed manifolds, one for each plant support structure, each water feed manifold extending along the series of rooting compartments of the associated plant support structure, a plurality of irrigation connections, one for each rooting compartment, respectively placing the interior of the water feed manifold in flow communication with the interiors of the rooting compartments; and in this construction the part of the water feed network upstream of the water feed manifolds may include a grid of pipes at a level at or above the upper extremities of the plant support structures, each water feed manifold being suspended by, and depending downwardly from one of the pipes of the grid, the part of the water feed network upstream thereof, each irrigation connection including an irrigation nozzle and discharging into the associated rooting compartment at a level above the midpoint, in the vertical direction, of that compartment.
Similarly, the water drainage network may comprise a water drainage reticulation system leading from each plant support structure to the reservoir, there conveniently being a water drainage manifold, forming part of the water drainage reticulation system, associated with each plant support structure and extending along the series of rooting compartments thereof, the manifold being connected to and in flow communication with the interior of each rooting compartment, for draining water, eg under gravity, from that rooting compartment to the drainage reticulation system. Conveniently the drainage reticulation system is at a low level, at or below the lower extremities of the plant support structures. In a particular construction, eg when the plant support structures are plant support columns, each water drainage manifold may extend along the interior of the associated column, along the series of compartments and through each compartment, there being at least one drainage opening from the interior of each compartment into the interior of the drainage manifold, preferably at a low level in that compartment and below any water feed into that compartment. The drainage manifold may have a plurality of outward projections or protrusions such as shoulders spaced along its length, the protrusions acting respectively to support the constrictions of the sleeve, each protrusion conveniently being spaced closely below the or each drainage opening from the compartment located immediately above that protrusion. In other words, the water drainage network may include a plurality of water drainage manifolds, one for each plant support structure, each water drainage manifold extending along the series of rooting compartments of the associated plant support structure. In this case, each water drainage manifold may extend along the interiors of the rooting compartments of the associated plant support structure, there being at least one drainage opening from each rooting compartment, at a level below the midpoint, in the vertical direction, of that compartment, and leading into the interior of the drainage manifold, the part of the drainage network downstream of the drainage manifolds including a grid of pipes at a level at or below the lower extremities of the plant support structures and the water drainage manifolds projecting upwardly from the pipes of this grid; and each plant support structure may be in the form of a plant support column divided by a plurality of constrictions, spaced along the column, into the rooting compartments, each drainage manifold having a plurality of protrusions standing proud of its outer surface and spaced along its length, each constriction being supported by an associated one of the protrusions and each drainage opening of the rooting compartment above that constriction passing through the drainage pipe at a position closely spaced above the protrusion which supports that constriction.
Typically, the water circulation means will be a pump, between the reservoir and the plant support structures. The pump is preferably downstream in the circuit from the reservoir and upstream from the plant support structures, for pumped flow along the water feed network and gravity flow along the water drainage network, although, instead, the pump may be upstream of the reservoir and downstream of the plant support structures, for pumped flow along the water drainage network and gravity flow along the water feed network.
When the parts of the apparatus are releasably connected to each other, the plant support structures in particular may be releasably connected to the water feed network and the water drainage network, in which case they may be portable to allow them, and plants rooted in their rooting compartments, to be carried to a different environment, such as that provided by a cold room or hothouse, to induce or break dormancy, to accelerate growth, or similarly control plant growth.
The invention extends to a second aspect which is a method for the hydroponic cultivation of plants, the method comprising:
circulating water containing dissolved plant nutrients from a reservoir containing the water along a water feed network comprising a plurality of water flow conduits to a plurality of horizontally spaced upwardly projecting plant support structures;
feeding water from the water feed network into each of the plant support structures, the water fed to each plant support structure being fed separately from the water feed network into each of a plurality of rooting compartments containing plant rooting medium and arranged in a series extending over the height of the plant support structure;
draining water separately from each of the plant rooting compartments of each plant support structure into a water drainage network comprising a plurality of water drainage conduits; and
circulating water drained from the rooting compartments along the water drainage conduits from the plant support structures to the reservoir, the plants being cultivated having roots rooted in the rooting medium in the rooting compartments and having foliage protruding from openings in walls of the rooting compartments.
By the rooting compartments"" being separately fed from the water feed network, and by the rooting compartments"" being separately drained into the water drainage network, is meant that the compartments are fed in parallel with water from the feed network, and drain in parallel into the drainage network, there being no flow of water in series through the compartments.
Circulating the water may be provided by pumping the water, and may be continuous or, preferably, intermittent. The method may include adding make-up water and make-up nutrients to the water, eg in the reservoir, as required. It is further contemplated that, in accordance with the cultivation method of the present invention, the plant support structures can be disconnected from the water feed network and from the water drainage network, thereafter being moved to a cooler or warmer environment, as desired, to induce or break dormancy, to induce flowering or fruiting, or the like, before being reintroduced into the circuit formed, together with the plant support structures, by the reservoir, water feed network and water drainage network. Furthermore, as and when desired, air can be circulated around the circuit, the reservoir and any water circulation means being replaced by a fan or blower. This can act to dry and aerate/oxygenate the plant rooting medium, to remove undesirable gases therefrom, to heat or cool the rooting medium with hot or cold air, and/or to introduce gaseous disinfectants or pesticides such as methyl bromide to the rooting medium. Indeed, the circulating water containing plant nutrients can be used to carry dissolved pesticides to the rooting medium.
The invention extends further to a plant support structure for an apparatus or installation for the hydroponic cultivation of plants, the structure including a plurality of plant rooting compartments for holding plant rooting medium for rooting at least one plant in each compartment with the foliage of the plant outside the compartment, the compartments being arranged in a series extending between a pair of spaced extremities of the structure, the structure further including a hollow water drainage manifold in the form of a conduit having a wall defining a hollow interior of the manifold, the manifold being connected to the series of compartments with its interior in communication with the interior of each compartment, there being a separate connection for each compartment, for draining water from the compartments.
The support structure is thus adapted to have the plant rooting compartments receive water in parallel from a water feed network, the rooting compartments discharging such water in parallel into the drainage manifold, e.g. through a porous part of the manifold wall in each compartment, or preferably through an opening in the manifold wall in each compartment.
The structure may be in the form of an elongated column, the spaced extremities being at opposite ends of the column, the column including a sleeve of flexible material containing particulate plant rooting medium, the sleeve being divided by a plurality of constrictions, spaced along the length of the column, into the rooting compartments. The drainage manifold may extend along the interiors of the rooting compartments from one extremity of the series to the other, the manifold having a plurality of protrusions standing proud of its other surface and spaced along its length, each protrusion being associated with one of the constrictions, the column having an upright condition in which its is oriented with one of the extremities forming a lowermost extremity and the other extremity forming an uppermost extremity, each constriction being supported by the associated protrusion in said upright condition of the column, the sleeve being of impervious material and each constriction being provided by a tie under tension and extending around the associated sleeve.
In a particular embodiment, the drainage manifold may extend along the interiors of the rooting compartments from one extremity of the series to the other, there being at least one drainage opening through the wall of the manifold in each compartment, the drainage opening leading from said compartment into the interior of the manifold, the openings being located at positions in the compartments which permit drainage of water from the compartments when the structure is oriented in an upright condition in which one of the extremities is a lowermost extremity and the other extremity is an uppermost extremity.
Other features of the plant support structure may be as described either hereinabove with reference to the apparatus or installation or method of the present invention, or herebelow with reference to the drawings. In this regard it is explicitly noted that the various features of the various optional or preferred embodiments defined herein of the apparatus or installation, of the method or of the plant support structure need not be employed simultaneously, and some may be retained while others are omitted or have equivalents substituted therefor. Thus, various additional embodiments of the apparatus or installation, of the method and of the present support structure can be made up, using various different combinations of features of the present invention, other than those specifically defined above.
It is contemplated that each support structure will typically be constructed in more or less complete form, with its compartments and plant rooting medium in place, and will be distributed or shipped in this form to users, who will employ the structures in assembling the apparatus or installation of the invention. The compartments may in this case be made without any holes or openings such as slits in their walls for receiving plants or for receiving irrigation water supply nozzles, such holes, openings or slits being made on site by users when the apparatus or installation is assembled and/or when the plants are planted in the rooting medium in the compartments.
It is a major advantage of the invention that each plant support structure or column can support a plurality of plants with the plants in vertically spaced relationship, thereby increasing the plant density in terms of plants/floor area. Thus the number of plants, depending on the height of the plant support structures, which can be cultivated on any surface area, such as on the floor of a cultivation tunnel, can be increased by a factor of 10-40, or more.